Unitary evolution in Gowdy cosmology

Recent results on the nonunitary character of quantum time evolution in the family of Gowdy T³ spacetimes bring the question of whether one should abandon the most sacred principle of unitary evolution in cosmology. In this work we show that the answer is in the negative. We put forward a full nonperturbative canonical quantization of the polarized Gowdy T³ model that implements the dynamics while preserving unitarity. We discuss possible implications of this result.